I tried to implement a moveset full of (spoilery) nods, but that also is tricky to deal with, in a way that figuring out Monokuma is like solving a mystery, since this is a key aspect of the source games. This also works based on the fact that Monokuma is annoying in-universe as well.
Monokuma has a certain "gimmick" on its moveset, so I will be skipping the moves that use it, and explain them later.
Entrance: Monokuma pops from the ground exactly like he does when introducing himself in DR1/2, most commonly before giving out motives in DR1.
Special Attacks
Neutral Special - "Truth Bullet". Monokuma charges and shoots a Truth Bullet at the opponent, while yelling variations of "No, that's wrong!". Each bullet can have a random word written on it like "despair", "hope", "future", etc. Can be stored. BONUS: Kirby will yell the classic sentence.
Up Special - "Blast Off!", Monokuma rides the rocket that is used on Jin's/Kaito's Punishment, causing damage on its way, and then crash-landing it. The trajectory would be similar to Dedede's Up B. Monokuma may exit the rocket mid-tragectory (going free-fall) or not, but if he doesn't, the impact causes extra damage, similar to Villager's Lloyd Rocket. An ideal move for tricking the opponent.
Side Special - "Monokubs". Monokuma launches a random Monokub. While the special button is pressed, Monokuma holds a button and the Monokub keeps walking. When the player lets go of the buttom, Monokuma presses his buttom and explodes the Monokub. Reflects the very "caring" nature of Monokuma shown thoughout DRV3.
Down Special - Part of the gimmick. I'll explain it later.
Smash Attacks
Up Smash - Spears of Gungnir. Doesn't have great launching power, but cause more damage than average. Has a sweetspot which can pin the opponents. Used in Junko/Mukuro's murder. This is easiest attack to imagine if you know the source.
Side Smash - Part of the gimmick. I'll explain it later.
Down Smash - Flamethrower - Monokuma used a flamethrower to jump and blast flames below him, covering a big horizontal range. Used in Gonta's Punishment, and also somewhat references Celes' Punishment.
Tilt Attacks
Jab - Regular punches that end in the uppercut used agains Monomi.
Up Tilt - MEAT THE BONE ON. Monokuma gets down and points a skewer upwards, similar to how Teruteru kills the Ultimate Imposter
Side Tilt - Monokuma uses a salmon as a punching bag, which can hit opponents. References a scene in the anime.
Down Tilt - Monokuma picks up the Monokuma File, similar to Villager's Down Tilt, but with less damage/knockback and covering a bigger area.
Aerials
Neutral Air - Monokuma extends his claws to keep opponents away. I'm not sure if Monokuma should spin while doing so or not.
Up Air - Monokuma just swings a salmon above him.
Forward Air - Monokuma blasts the bazooka used in the fight against Akane/Nekomaru in DR2, covering a short area and launching him backwards.
Back Air - Monokuma grabs Monomi her by her feet and spins her, hitting opponents. References any interaction between the two of them in DR2.
Down Air - Part of the gimmick, i'll explain it later.
Grab moves
Grab - Monokuma launches a claw that can grab the opponent and bring it to him, similar to how Leon's/Teruteru's/Kaede's Punishment begun. Can grab ledges, but can't damage opponents mid-air.
Pummel - Monokuma repeatedly used his gavel agains the poor opponent's head.
Up Throw - Monokuma flings his arms upwards and throws the opponent, similar to a sprite where he is yelling and doing a similar pose.
Forward Throw - Monokuma swings a Truth Blade, launching the opponent.
Back Throw - The suplex Monomi repeatedly used on him when trying to kill him.
Down Throw - Smoke rises from the ground as Monokuma fights the opponent in a comic manner (like he did with Monomi many times), launching him afterwards.
Movement stuff
Run animation - The same goofy one from Ultra Despair Girls. Not very fast.
Dash Attack - A slash attack with his claws.
Final Smash
It's Punishment Time!
Monokuma uses his gavel to hit a bell, beggining Punishment time. He then disappears, and the screen gets covered by the same UI as the Nonstop Debate segments. The player can move a reticle during a select time (4 seconds?) and shoot players. After the time runs out, every player that got shot gets dragged away by a chain and ends up in Naegi/Kirigiri's Punishment, except the fighters are not on a chair, just layed down until they are crushed. Don't worry, they don't die, they only get comically launched afterwards.
This could be replaced by any other punishment, including an original one, but I tried to include the most iconic and spoiler-free in the franchise (because we can't determine who gets executed from this scenery alone).
Gimmick: The Murder Weapons
In Monokuma's Down Special, Monokuma can select between 5 truth bullets, in a menu similar to the one just before a Nonstop Debates.
But instead of selecting "evidence", the player can choose between 5 murder weapons, each of them being represented by a single command (up, down, left, right or Nothing), and having different properties. Besides that, the other players won't know what weapon was selected until Monokuma uses it.
Those weapons affect Monokuma's Forward Smash and Down Aerial. In the case of the Down Aerial, Monokuma launches itself downwards while holding said weapon.
Without further delay, the weapons are:
- Baseball Bat. Used in Mahiru's murder, also referencing Leon's Punishment. Has a bigger launch rate.
- Hammer. NOT used in Mechamaru's Murder. Also references Hifumi's/Taka's murder. Does more damage to shields, despite the lower range. Spikes if used in the Down Aerial.
- Shot Put Ball. Used in Rantaro's murder. Is thrown, rather than swung. Can be a edgeguarding tool. Is not thrown on the down aerial.
- Wooden Plank. Used in Angie's/Tenko's/Ryoma's murder. Has a bigger range. Also includes seesaw jokes in Smash.
- Bomb. Not a weapon per se, but makes Monokuma self-destruct, with a little alarm ringing beforehand. References every instance of him blowing up, and kind of references Keebo's death in DRV3. Also kind of references every instance where there was no murder, but a suicide.
Taunts
Down Taunt - Monokuma charges energy like he does in 2-6 before transforming into Giga Junko.
Side Taunt - Monokuma unleashes his classic laughter (Upupupu/Puhuhuhu) while covering his mouth.
Up Taunt - The dance he does in the anime opening.
Victory Animations
Monokuma sitting on a chair while holding a beverage, tauntingly looking at the screen, like he appears in most games.
Monokuma Losing His **** from laughing too hard, similar to Wario.
Smoke covering the screen, then revealing Monokuma in its Junko pose (without Junko, obviously)
Alternate colors
Shirokuma
Kurokuma
Conductor Monokuma (the outfit he used in Kaede's Punishment)
Worker Monokuma (the outfit he used in Alter Ego's Punishment. It is also used in V3 when revealing that the motive video for Ryoma is empty)
Beach Monokuma (the outfit used in promotional material for DR2)
Teacher Monokuma (the outfit used in Naegi's/Kirigiri's Punishment)
Alter-Ego Monokuma (similar to the Hidden Monokumas of 2-6, also paying homage to Alter Ego Chihiro/Junko/Gonta)
No Monokubs/Monomi here, since they are a part of the moveset.
Dizzy Animation: Monokuma just sits and moves his head, identical to how he looks after spinning too much in Mondo's Punishment.
Kirby: When Kirby inhales Monokuma, he basically becames Ball Monokuma from Ultra Despair Girls, which is hilarious.